/Engine/Source/Runtime/Engine/Classes/Kismet/ImportanceSamplingLibrary.h
Distribute sample points proportional to Texture2D luminance.
static void ImportanceSample ( const [FImportanceTexture](API\Runtime\Engine\Kismet\FImportanceTexture) & Texture, const FVector2D & Rand, int Samples, float Intensity, FVector2D & SamplePosition, [FLinearColor](API\Runtime\Core\Math\FLinearColor) & SampleColor, float & SampleIntensity, float & SampleSize )